BUG: remove millisecond field that raises valueerror

[llllllllll]

This would appear in the dir and cause tab completion to a field that would raise a ValueError. When I brought this up in gitter it seemed like it was safe to remove it.

I couldn't find any tests that hit this descriptor.

[jreback]

yeh, I think this was historicaly left in. can you add a test (assert that it raises), so when someone tries to add it back it will fail!. ping on green.

[llllllllll]

Added the test, build is now passing

[jreback]

thanks!